LXR linux/drivers/rtc/rtc-ab3100.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2007-2009 ST-Ericsson AB
   4 * RTC clock driver for the AB3100 Analog Baseband Chip
   5 * Author: Linus Walleij <linus.walleij@stericsson.com>
   6 */
   7#include <linux/module.h>
   8#include <linux/kernel.h>
   9#include <linux/init.h>
  10#include <linux/platform_device.h>
  11#include <linux/rtc.h>
  12#include <linux/mfd/abx500.h>
  13
  14/* Clock rate in Hz */
  15#define AB3100_RTC_CLOCK_RATE   32768
  16
  17/*
  18 * The AB3100 RTC registers. These are the same for
  19 * AB3000 and AB3100.
  20 * Control register:
  21 * Bit 0: RTC Monitor cleared=0, active=1, if you set it
  22 *        to 1 it remains active until RTC power is lost.
  23 * Bit 1: 32 kHz Oscillator, 0 = on, 1 = bypass
  24 * Bit 2: Alarm on, 0 = off, 1 = on
  25 * Bit 3: 32 kHz buffer disabling, 0 = enabled, 1 = disabled
  26 */
  27#define AB3100_RTC              0x53
  28/* default setting, buffer disabled, alarm on */
  29#define RTC_SETTING             0x30
  30/* Alarm when AL0-AL3 == TI0-TI3  */
  31#define AB3100_AL0              0x56
  32#define AB3100_AL1              0x57
  33#define AB3100_AL2              0x58
  34#define AB3100_AL3              0x59
  35/* This 48-bit register that counts up at 32768 Hz */
  36#define AB3100_TI0              0x5a
  37#define AB3100_TI1              0x5b
  38#define AB3100_TI2              0x5c
  39#define AB3100_TI3              0x5d
  40#define AB3100_TI4              0x5e
  41#define AB3100_TI5              0x5f
  42
  43/*
  44 * RTC clock functions and device struct declaration
  45 */
  46static int ab3100_rtc_set_time(struct device *dev, struct rtc_time *tm)
  47{
  48        u8 regs[] = {AB3100_TI0, AB3100_TI1, AB3100_TI2,
  49                     AB3100_TI3, AB3100_TI4, AB3100_TI5};
  50        unsigned char buf[6];
  51        u64 hw_counter = rtc_tm_to_time64(tm) * AB3100_RTC_CLOCK_RATE * 2;
  52        int err = 0;
  53        int i;
  54
  55        buf[0] = (hw_counter) & 0xFF;
  56        buf[1] = (hw_counter >> 8) & 0xFF;
  57        buf[2] = (hw_counter >> 16) & 0xFF;
  58        buf[3] = (hw_counter >> 24) & 0xFF;
  59        buf[4] = (hw_counter >> 32) & 0xFF;
  60        buf[5] = (hw_counter >> 40) & 0xFF;
  61
  62        for (i = 0; i < 6; i++) {
  63                err = abx500_set_register_interruptible(dev, 0,
  64                                                        regs[i], buf[i]);
  65                if (err)
  66                        return err;
  67        }
  68
  69        /* Set the flag to mark that the clock is now set */
  70        return abx500_mask_and_set_register_interruptible(dev, 0,
  71                                                          AB3100_RTC,
  72                                                          0x01, 0x01);
  73
  74}
  75
  76static int ab3100_rtc_read_time(struct device *dev, struct rtc_time *tm)
  77{
  78        time64_t time;
  79        u8 rtcval;
  80        int err;
  81
  82        err = abx500_get_register_interruptible(dev, 0,
  83                                                AB3100_RTC, &rtcval);
  84        if (err)
  85                return err;
  86
  87        if (!(rtcval & 0x01)) {
  88                dev_info(dev, "clock not set (lost power)");
  89                return -EINVAL;
  90        } else {
  91                u64 hw_counter;
  92                u8 buf[6];
  93
  94                /* Read out time registers */
  95                err = abx500_get_register_page_interruptible(dev, 0,
  96                                                             AB3100_TI0,
  97                                                             buf, 6);
  98                if (err != 0)
  99                        return err;
 100
 101                hw_counter = ((u64) buf[5] << 40) | ((u64) buf[4] << 32) |
 102                        ((u64) buf[3] << 24) | ((u64) buf[2] << 16) |
 103                        ((u64) buf[1] << 8) | (u64) buf[0];
 104                time = hw_counter / (u64) (AB3100_RTC_CLOCK_RATE * 2);
 105        }
 106
 107        rtc_time64_to_tm(time, tm);
 108
 109        return 0;
 110}
 111
 112static int ab3100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 113{
 114        time64_t time;
 115        u64 hw_counter;
 116        u8 buf[6];
 117        u8 rtcval;
 118        int err;
 119
 120        /* Figure out if alarm is enabled or not */
 121        err = abx500_get_register_interruptible(dev, 0,
 122                                                AB3100_RTC, &rtcval);
 123        if (err)
 124                return err;
 125        if (rtcval & 0x04)
 126                alarm->enabled = 1;
 127        else
 128                alarm->enabled = 0;
 129        /* No idea how this could be represented */
 130        alarm->pending = 0;
 131        /* Read out alarm registers, only 4 bytes */
 132        err = abx500_get_register_page_interruptible(dev, 0,
 133                                                     AB3100_AL0, buf, 4);
 134        if (err)
 135                return err;
 136        hw_counter = ((u64) buf[3] << 40) | ((u64) buf[2] << 32) |
 137                ((u64) buf[1] << 24) | ((u64) buf[0] << 16);
 138        time = hw_counter / (u64) (AB3100_RTC_CLOCK_RATE * 2);
 139
 140        rtc_time64_to_tm(time, &alarm->time);
 141
 142        return rtc_valid_tm(&alarm->time);
 143}
 144
 145static int ab3100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 146{
 147        u8 regs[] = {AB3100_AL0, AB3100_AL1, AB3100_AL2, AB3100_AL3};
 148        unsigned char buf[4];
 149        time64_t secs;
 150        u64 hw_counter;
 151        int err;
 152        int i;
 153
 154        secs = rtc_tm_to_time64(&alarm->time);
 155        hw_counter = secs * AB3100_RTC_CLOCK_RATE * 2;
 156        buf[0] = (hw_counter >> 16) & 0xFF;
 157        buf[1] = (hw_counter >> 24) & 0xFF;
 158        buf[2] = (hw_counter >> 32) & 0xFF;
 159        buf[3] = (hw_counter >> 40) & 0xFF;
 160
 161        /* Set the alarm */
 162        for (i = 0; i < 4; i++) {
 163                err = abx500_set_register_interruptible(dev, 0,
 164                                                        regs[i], buf[i]);
 165                if (err)
 166                        return err;
 167        }
 168        /* Then enable the alarm */
 169        return abx500_mask_and_set_register_interruptible(dev, 0,
 170                                                          AB3100_RTC, (1 << 2),
 171                                                          alarm->enabled << 2);
 172}
 173
 174static int ab3100_rtc_irq_enable(struct device *dev, unsigned int enabled)
 175{
 176        /*
 177         * It's not possible to enable/disable the alarm IRQ for this RTC.
 178         * It does not actually trigger any IRQ: instead its only function is
 179         * to power up the system, if it wasn't on. This will manifest as
 180         * a "power up cause" in the AB3100 power driver (battery charging etc)
 181         * and need to be handled there instead.
 182         */
 183        if (enabled)
 184                return abx500_mask_and_set_register_interruptible(dev, 0,
 185                                                    AB3100_RTC, (1 << 2),
 186                                                    1 << 2);
 187        else
 188                return abx500_mask_and_set_register_interruptible(dev, 0,
 189                                                    AB3100_RTC, (1 << 2),
 190                                                    0);
 191}
 192
 193static const struct rtc_class_ops ab3100_rtc_ops = {
 194        .read_time      = ab3100_rtc_read_time,
 195        .set_time       = ab3100_rtc_set_time,
 196        .read_alarm     = ab3100_rtc_read_alarm,
 197        .set_alarm      = ab3100_rtc_set_alarm,
 198        .alarm_irq_enable = ab3100_rtc_irq_enable,
 199};
 200
 201static int __init ab3100_rtc_probe(struct platform_device *pdev)
 202{
 203        int err;
 204        u8 regval;
 205        struct rtc_device *rtc;
 206
 207        /* The first RTC register needs special treatment */
 208        err = abx500_get_register_interruptible(&pdev->dev, 0,
 209                                                AB3100_RTC, &regval);
 210        if (err) {
 211                dev_err(&pdev->dev, "unable to read RTC register\n");
 212                return -ENODEV;
 213        }
 214
 215        if ((regval & 0xFE) != RTC_SETTING) {
 216                dev_warn(&pdev->dev, "not default value in RTC reg 0x%x\n",
 217                         regval);
 218        }
 219
 220        if ((regval & 1) == 0) {
 221                /*
 222                 * Set bit to detect power loss.
 223                 * This bit remains until RTC power is lost.
 224                 */
 225                regval = 1 | RTC_SETTING;
 226                err = abx500_set_register_interruptible(&pdev->dev, 0,
 227                                                        AB3100_RTC, regval);
 228                /* Ignore any error on this write */
 229        }
 230
 231        rtc = devm_rtc_allocate_device(&pdev->dev);
 232        if (IS_ERR(rtc))
 233                return PTR_ERR(rtc);
 234
 235        rtc->ops = &ab3100_rtc_ops;
 236        /* 48bit counter at (AB3100_RTC_CLOCK_RATE * 2) */
 237        rtc->range_max = U32_MAX;
 238
 239        platform_set_drvdata(pdev, rtc);
 240
 241        return rtc_register_device(rtc);
 242}
 243
 244static struct platform_driver ab3100_rtc_driver = {
 245        .driver = {
 246                .name = "ab3100-rtc",
 247        },
 248};
 249
 250module_platform_driver_probe(ab3100_rtc_driver, ab3100_rtc_probe);
 251
 252MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
 253MODULE_DESCRIPTION("AB3100 RTC Driver");
 254MODULE_LICENSE("GPL");
 255